As an X-ray imaging device provided with an X-ray detector (Flat Panel Detector: FPD) in which conversion elements generating electric signals according to emitted X-rays are arranged and which reads the electric signals generated by the conversion elements as image signals, there is known, for example, an X-ray imaging device with a Talbot interferometer or Talbot-Lau interferometer provided with an X-ray source which emits X-rays to an X-ray detector, a plurality of diffraction gratings and so forth (refer to, for example, Patent Documents 1 to 3).
The Talbot interferometer or Talbot-Lau interferometer utilizes the Talbot effect of forming a grating image at constant intervals in a light traveling direction of coherent light when the light has passed through a first grating which is provided with slits arranged at predetermined intervals. The Talbot interferometer or Talbot-Lau interferometer forms moire fringes by a second grating being arranged at a position where a grating image of the first grating is formed with the grating direction of the second grating slightly inclined with respect to the direction of the first grating. When an object is arranged in front of the second grating, the moire is deformed. Hence, a reconstructed image(s) of a subject can be obtained by irradiating the subject arranged in front of or behind the first grating with coherent X-rays and performing mathematical operation on the obtained images of moire fringes (called “moire images”).
It is known that at least three types of images, an X-ray absorption image, a differential phase image and a small-angle scattering image, can be generated by analyzing the moire images with a method based on the principles of the fringe scanning method (refer to, for example, Non-Patent Documents 1 and 2) or analyzing the moire images with the Fourier transform method (refer to, for example, Non-Patent Document 3), for example. It has been confirmed that a cartilage of a joint part can be depicted in, among these, the differential phase image (refer to, for example, Non-Patent Documents 4 and 5).
The inventors of this application and others have modified the X-ray imaging device with a Talbot interferometer or Talbot-Lau interferometer and succeeded in imaging a cartilage of a joint part at least in a differential phase image by taking moire images of not a joint part in a dissected state as in the above but a joint part in a living body and performing reconstruction thereon.
That is, as indicated by A1 in FIG. 9, according to the studies by the inventors of this application and others, it has been found out that a cartilage of a joint part can be imaged in a differential phase image obtained by performing reconstruction on moire images taken by an X-ray imaging device with a Talbot interferometer or Talbot-Lau interferometer. In FIG. 9, the edge of the cartilage of the joint part is imaged as a streak between two bones which constitute the joint part.